1. Field of the Invention
The present invention relates to a display device for preventing corrosion of a signal line. Particularly, the present invention relates to a display device, such as an organic electroluminescent device, for preventing a scan line or a data line from being corroded.
2. Description of the Related Art
An organic electroluminescent device, one of the display devices, is a device using organic electroluminescence. Organic electroluminescence is a phenomenon that excitons are formed in an (low molecular or high molecular) organic material thin film by re-combining holes injected through an anode with electrons injected through a cathode, and a light of specific wavelength is generated by energy of the formed excitons.
FIG. 1 is a cross-sectional view of an organic electroluminescent device of the related art.
As shown in FIG. 1, the organic electroluminescent device comprises an anode electrode layer 2, an insulating layer (not shown), an organic material layer 3 and a cathode electrode layer 4, stacked in order on a glass substrate 1. A wall W is formed on the anode electrode layers 2 for partitioning the cathode electrode layers 4.
The anode electrode layer 2 is coupled to pads (not shown) disposed on an end of the substrate 1 through a data line, and the cathode electrode layer 4 is coupled to the pads through a scan line.
FIG. 2 shows a cross-sectional view of the data line or the scan line of the organic electroluminescent device, in accordance with the related art. Hereinafter, for convenience's sake, the scan line will be exemplified.
The scan line 10 comprises a scan line electrode layer 10a disposed on the substrate 1, and a sub-electrode layer 10b disposed on the scan line electrode layer 10a. Usually, ITO is used for the scan line electrode layer 10a, and molybdenum, which has a lower resistance value than ITO, is used for the sub-electrode layer 10b. Therefore, the overall resistance of the scan line 10 can be reduced.
The scan line 10 is disposed within an area applied by sealant 5 (hereinafter, referred to as “sealant area”), where a cap 6 is attached to the substrate 1. In this area, the sealant 5 is disposed between the scan line 10 and the cap 6.
After the cap 6 is attached to the substrate 1 by the sealant 5, the sealant 5 disposed between the cap 6 and the substrate 1 should be cured by ultraviolet ray passing through the substrate 1. However, the ultraviolet ray cannot pass through the sub-electrode layer 10b of the sealant area, which is made of metal.
Therefore, the sealant 5 applied on the scan line 10 is not completely cured, which weakens the attaching force between the cap 6 and the substrate 1. Therefore, the moisture contained in the air may permeate into the inside of the cap 6, and degrade the device.
In addition, the scan line 10 having a double-layer structure may be corroded by moisture contained in atmosphere or moisture contained in sealant 5. Particularly, galvanic corrosion may occur on the boundary surfaces of the scan line electrode layer 10a and the sub-electrode layer 10b. 
The galvanic corrosion occurred on the boundary surfaces of the scan line electrode layer 10a and the sub-electrode layer 10b decreases the brightness of the organic electroluminescent device by increasing a resistance value of the scan line 10, and increases the power consumption of the device such that the entire performance of the device is degenerated.